The present invention relates to shut height adjustment mechanisms, and, more particularly, to a new and improved mechanism for adjusting the shut height between two members which are reciprocally displaced relative to each other by toggle linkages.
In its simplest form, a toggle linkage consists of a pair of links pivotally joined at adjacent ends. The far end of one of the links is pivoted about a fixed point; while the far end of the other link is adapted for linear motion. In such toggle linkages a small force at the juncture of the two links produces a much larger force at the far end of the other link. Accordingly, toggle linkages are commonly used in presses and crushers.
In the packaging industry, each of a pair of forming or sealing dies is mounted to a respective press plate for relative movement with respect to the other die between an open position, facilitating accommodation therebetween of a formable or sealable material, and a closed position, facilitating forming or sealing of the material. Toggle linkages are connected to the press plates for controlling the movement of the dies. With the press plates in the closed position, the links comprising each toggle linkage are usually aligned linearly to maximize the force capable of being applied through the toggle linkage, the distance between the press plates being referred to in the industry as the shut height. Depending upon the particular material to be formed or sealed, the size and shape of the dies change from one sealing or forming operation to the next. Thus, there is a need to adjust the shut height so that different dies may be used interchangeably without adversely affecting the forming or sealing operation. Likewise, in laminating, trimming, and other operations wherein material engaging members or tools close on inserted material, ordinary variances within the tolerance to which the tools are machined require fine adjustment to assure a proper shut height.